Method of producing a green flame by aspirating trimethyl borate



United States Patent Int. Cl. C06d 1/10 US. Cl. 149-22 3 Claims ABSTRACT OF THE DISCLOSURE A method for producing a colored flame comprising first dissolving trimethyl borate in methanol and then aspirating the solution of trimethyl borate and methanol in a high temperature flame.

Background of the invention The present invention relates to a method for producing a colored flame and more particularly to a method for producing a colored flame which has utility as a military signaling flare.

Various types of devices and compositions have heretofore been used as flares by the military forces. For example, in US. Patent 3,258,373, which issued June 28, 1966, to Bernard E. Douda, there is disclosed a castable pyrotechnic composition of strontium perchlorate and an acrylic monomer which composition has use as a military flare.

Another composition having utility by the military is disclosed in US. Patent 2,796,339, which issued June 18, 1957, to Leonard D. Jackson. This patent relates to a pyrotechnic mixture for use in a signal flare and in incendiary and self destroying devices. The ingredients are between 60 and 90 percent strontium nitrate and between 10 and 40 percent boron.

As there are many different applications and conditions for which a military flare may be employed, numerous devices and formulas must be utilized to serve the needs of the military forces. For example, flares are launched from submarines, aircraft, and from the surface and, when ignited, generate a flame, flash, infrared radiation, smoke, or sound display (or combinations of these effects) for a broad variety of purposes. These purposes include visual and audible signaling, area or target illumination, reference point marking, indication of practice weapon fuze action or impact, tracking, weapon effects simultation, and screening.

Summary of the invention The present invention relates to a method of coloring a flame so that the flame can be utilized as a military signaling device. A quantity of trimethyl borate is dissolved in methanol and then the solution is aspirated in a high temperature flame produced by burning a fuel in the presence of an oxidizer.

Description of the preferred embodiment Trimethyl borate, a colorless liquid, is first mixed with methanol in the ratio of between 5 and 30 percent, by

3,453,157 Patented July 1, 1969 volume, of trimethyl borate and between and percent of methanol. Then the solution of trimethyl borate and alcohol is aspirated into a very hot flame whereby the flame is colored a very intense green.

By way of specific example, a solution of trimethyl borate in methyl alcohol of approximately 10 percent concentration, was aspirated into an acetylene-oxygen flame about six inches high. The flame was green and produced a luminous intensity of about 30 candela. The flame temperature was about 3500 degrees C., and resulted from the stoichiometric combustion of oxygen and acetylene. An intense green flame was also produced when the same 10 percent solution was aspirated into a hydrogen-oxygen flame which had a temperature of about 2800 degrees C. The green colored flames produced were superior in luminous intensity to the various barium salts which are used in most green flame pyrotechnics.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. For example, while methanol was used as the solvent, other organic solvents might also be used. Methanol has particular advantage in that the solution would not freeze at temperatures above about l40 degrees F., nor boil below degrees F. Accordingly, exposure to temperature extremes which might be encountered in military field service would not be likely to cause malfunctions. Methanol is relatively cheap and readily available. Also, other compounds of boron, such as borazine, amineborane adducts, hexamethyl borazine and triethyl borate, which are soluble in the fuel, may be used.

We claim:

1. A method for producing a green flame comprising:

aspirating a solution of trimethyl borate dissolved in methanol into a high temperature flame produced by burning a fuel selected from the group consisting of acetylene and hydrogen in the presence of oxygen, said trimethyl borate present in a concentration of between 5 and 30 percent, by volume, and said methanol present in a concentration of between 70 and 95 percent, by volume.

2. A method of producing a green flame as set forth in claim 1 wherein said high temperature flame is produced by using acetylene as a fuel.

3. A method of producing a green flame as set forth in claim 1 wherein said high temperature flame is produced by using hydrogen as a fuel.

References Cited UNITED STATES PATENTS 2,107,613 10/1963 Armstrong et al. 14922 X 3,126,305 3/1964 Armstrong 149-22 X BENJAMIN R. PADGETT, Primary Examiner.

S. J. LECHERT, Assistant Examiner.

US. Cl. X.R. 1491, 109 

